1. Field of the Invention
The present invention relates to freezers, and, more particularly, to ice makers within freezers.
2. Description of the Related Art
The freezer portion of a refrigeration/freezer appliance often includes an ice cube maker which dispenses the ice cubes into a dispenser tray. A mold has a series of cavities, each of which is filled with water. The air surrounding the mold is cooled to a temperature below freezing so that each cavity forms an individual ice cube. As the water freezes, the ice cubes become bonded to the inner surfaces of the mold cavities.
In order to remove an ice cube from its mold cavity, it is first necessary to break the bond that forms during the freezing process between the ice cube and the inner surface of the mold cavity. In order to break the bond, it is known to heat the mold cavity, thereby melting the ice contacting the mold cavity on the outermost portion of the cube. The ice cube can then be scooped out or otherwise mechanically removed from the mold cavity and placed in the dispenser tray. A problem is that, since the mold cavity is heated and must be cooled down again, the time required to freeze the water is lengthened.
Another problem is that the heating of the mold increases the operational costs of the ice maker by consuming electrical power. Further, this heating must be offset with additional refrigeration in order to maintain a freezing ambient temperature, thereby consuming additional power. This is especially troublesome in view of government mandates which require freezers to increase their efficiency.
Yet another problem is that, since the mold cavity is heated, the water at the top, middle of the mold cavity freezes first and the freezing continues in outward directions. In this freezing process, the boundary between the ice and the water tends to push impurities to the outside of the cube. Thus, the impurities become highly visible on the outside of the cube and cause the cube to have an unappealing appearance. Also, the impurities tend to plate out or build up on the mold wall, thereby making ice cube removal more difficult.
A further problem is that vaporization of the water in the mold cavities causes frost to form on the walls of the freezer. More particularly, in a phenomenon termed xe2x80x9cvapor flashingxe2x80x9d, vaporization occurs during the melting of the bond between the ice and the mold cavity. Moreover, vaporization adds to the latent load or the water removal load of the refrigerator.
Yet another problem is that the ice cube must be substantially completely frozen before it is capable of withstanding the stresses imparted by the melting and removal processes. This limits the throughput capacity of the ice maker.
What is needed in the art is an ice maker which does not require heat in order to remove ice cubes from their cavities, has an increased throughput capacity, allows less evaporation of water within the freezer, eases the separation of the ice cubes from the auger and does not push impurities to the outer surfaces of the ice cubes.
The present invention provides a control system and corresponding method of operation which allows ice cubes to be automatically harvested in an efficient manner.
The invention comprises, in one form thereof a method of making ice in an automatic ice maker, including the steps of: providing a mold including at least one cavity; filling the at least one mold cavity at least partially with water, providing an ice removal device at least partly within the at least one mold cavity; coupling a mechanical drive with the ice removal device; coupling a controller with the drive; measuring a temperature of the mold; measuring an ambient temperature associated with the mold; and controlling operation of the drive using the controller, dependent upon the measured temperature of the mold and the measured ambient temperature.
The invention comprises, in another form thereof, an ice maker including a mold with at least one cavity for containing water therein for freezing into ice. A mold temperature sensor is positioned in association with a mold and provides an output signal indicative of a temperature of the mold. An ambient temperature sensor provides output signal indicative of an ambient temperature associated with the mold. An ice removal device is at least partly positioned within the at least one mold cavity. The mechanical drive drives the ice removal device. A controller is coupled with each of the mold temperature sensor, the ambient temperature sensor and the drive. The controller controls operation of the drive dependent upon the output signal from the mold temperature sensor and the output signal from the ambient temperature sensor.
An advantage of the present invention is that ice cubes may automatically be harvested depending upon the temperature of the mold, thereby increasing the throughput rate of the ice maker.
Another advantage is that the time period necessary for freezing the ice may be calculated without continuously sensing and memorizing the temperature of the mold.
Yet another advantage is that the time period necessary for freezing the ice may be adjusted automatically based upon changing environmental conditions within the freezer which affect the temperature gradient of the freezing. That provides for better cube quality: no soft cubes, no hollow cubes, no broken cubes.
A further advantage is that filling of the mold cavity does not occur until the temperature of the mold has decreased to a point where freezing may begin occurring after filling, so no double fills will occur.
Another advantage is that a frozen or blocked fill tube may be sensed and heat applied thereto for the purpose of clearing the fill tube.